Year	% net
1977	8.65811
1978	8.82818
1979	9.14551
1980	9.57869
1981	9.66318
1982	10.39239
1983	11.00478
1984	11.41344
1985	11.51284
1986	11.65943
1987	11.96165
1988	12.21432
1989	12.42829
1990	12.23489
1991	13.06968
1992	13.83817
1993	14.53872
1994	15.40615
1995	16.64963
1996	17.61427
1997	18.48274
1998	19.81688
1999	20.87408
2000	22.07151
2001	23.00724
2002	23.8927
2003	24.33862
2004	24.19485
2005	24.89336
2006	25.86584
2007	26.78616
2008	27.63794
2009	29.11726
2010	30.58352
2011	31.46895
2012	32.75704
2013	33.60878
2014	34.7161
2015	36.09961
2016	36.67048
2017	36.91462
2018	35.80764